Video input to a typical display system, such as a digital micromirror device (DMD) based display system, is usually in the form of stimuli containing three driving signals, such as luma-chroma (YUV), luma-chroma (blue)-chroma (red) (YCbCr), YPbPr, red-green-blue (RGB), and so forth. The stimuli with three driving signals can be expressed as three-dimensional color vectors. However, display systems that are multiprimary use stimuli that, in general, use N driving signals, where N is greater than or equal to three. Therefore, there is a need to convert the stimuli with three driving signals (the video input) into the stimuli with N driving signals used by the multiprimary display system (the display output).
The stimuli with N driving signals can then be displayed by the multiprimary display system. For example, in a single-chip DMD-based display system, the display system will sequentially display the colors of the stimuli and set individual micromirrors in the DMD to states that correspond to image data of an image being displayed. The image data used to set the states of the micromirrors also corresponds to the color currently being displayed by the display system. For instance, if the display system is displaying the color red, then only image data associated with the color red is being used to set the states of the micromirrors in the DMD.
Unless a desired color (or gray scale) being displayed is a sufficiently close match for the output of the display system, dithering (spatial and/or temporal) can be required to visually create the color. Dithering can make use of the blending of more than one color to create the desired color. For example, to display a 50 percent red color, the display system can display a 100 percent red color for 50 percent of the time and display no color for the remaining 50 percent of the time. The human eye will integrate the output of the display system into a 50 percent red color.
In some situations, a representation of an input color vector that uses darker colors may be preferred over a representation that uses only brighter colors or a combination of both darker and brighter colors. For example, when dark colored pixels are displayed, the use of representations of output color vectors using only colors that are darker can yield an improved quality image.